Many positioning and/or transfer assemblies incorporate conveyor belts to transport material or work pieces and position it at a desired location. In those applications a belt is used in the form of a continuous loop which is supported at opposite reversing ends by rollers or the like. The belt might be used for transferring an object from one place to another and/or to position an object on a desired location, for example for processing, treating or machining the object. Proper operation of these systems may require that the belt moves in a controlled way with minimal positioning errors. For example, in inkjet printers each individual color plane is in general transferred to the substrate at different locations along the travel path of the conveyor belt or other substrate carrier. Therefore the position of the object (or substrate as it is called in printing technology) on the conveyor belt needs to be very stable and reproducible, for example within ±10 μm, to insure that the resulting image is of good quality. Position errors of the conveyor belt may cause errors in the positioning of the object that is placed on the conveyor belt.